Valveless intermittent combustor with automatic flow control



May 1, 1956 w. B. BRZOZOWSKI VALVELESS INTERMITTENT COMBUSTOR WITH AUTOMATIC FLOW CONTROL Filed March 24, 1951 INVENTOR. W/fo/d 5. Brzozows/r/ Age/#5 United States Patent VALVELESS INTERMITTEN T COMBUSTOR WITH AUTOMATIC FLDW CONTROL Witold B. Brzozowski, Montreal-Outremont, Quebec, Canada Application March 24, 1951, Serial No. 217,387

4 Claims. (Cl. 60-35.6)

This invention relates to an intermittent combustor, and more particularly a valveless intermittent combustor. The invention is especially useful in its application to jet propulsion, to which use, however, it is not restricted.

In constructing intermittent combustors, as for use in jet propulsion, attempts have been made to design air inlet valves which are small, compact, efficient and durable, and which offer a minimum resistance to the air when the unit is in motion. Such attempts however, have not given satisfactory results. Consequently attempts have been made to provide intermittent combustors without air inlet valves. In designing valveless intermittent cornbustors, however, attention has heretofore been focused upon offering the least possible resistance to the iii-flow of air through the inlet passage while, at the same time, offering the greatest possible resistance to reverse flow of the products of combustion through that passage. Tests upon such combustors heretofore provided have indicated that their efficiency is so low as to make the apparatus impractical.

I have now found it possible to construct a valveless intermittent or pulse combustor in accordance with a different principle. This combustor is simple and .eflicient; and it has met practical tests proving its superior effectiveness.

in accordance with the invention, a minimum resistance is offered to the flow of air into the burner, but a minimum resistance is also oflt'ered to reverse movement of the products of combustion outwardly of the burner. By suitably changing the direction of the reversely flowing products of combustion they may be directed to move in the same direction as that of the air entering the burner, and their passage out of the burner may be utilized to give additional propulsive impulse to the unit where jet propulsion is contemplated.

The invention is illustrated by way of example in the accompanying drawing; wherein- Fig. 1 is an elevation of an intermittent combustor constructed in accordance with the invention, shown partly in longitudinal mid-section;

Fig. 2 is a broken longitudinal mid-section through the burner shown in Fig. 1 illustrating one phase of its cycle of operation;

Fig. 3 is a similar broken longitudinal mid-section through the same burner illustrating a subsequent phase of its cycle of operation;

Fig. 4 is a cross section taken on the line IVIV of Fig. 1; and

Fig. 5 is a broken elevation illustrating a variant form of the rear end of the burner.

In the embodiment of the invention which is illustrated in Figs. 1 to 4 inclusive, there is shown a valveless intermittent combustor comprising a tube 11 having a closed forward end 12, of smaller diameter than that of its main portion, and an open rear end 13. The tube 11 has a short transition section or shoulder 14 formed 2,743,575 fatenteol May 1, 1956 thereon by gradually or progressively reducing the diameter of its main portion toward its closed forward end 12. Angular openings 15 are thus provided in the tube 11 at its recessed shoulder 14 for admission of air into the tube. Thus, air moving from left to right as illustrated in Figs. 1, 2 and 3, relatively to the combustor, and about the closed forward end 12 of the tube 11 will readily enter the tube through the openings 15 therein.

A fuel ring 16 is positioned transversely of the tube 11 a short distance ahead of the openings 15 therein, being fixed in place in any known or convenient manner (not illustrated). The fuel ring 16 has spray orifices 17 extending through it and directed toward the rear of the tube 11. A fuel supply pipe 18 is connected to the fuel ring 16 to supply a fluid fuel thereto under pressure. Thus, the fuel ring 16 sprays fluid fuel into the tube 11 where the fuel mixes with air entering the tube through the openings 15 to form a combustible mixture. Igniting means, here illustrated as a spark plug 19 projecting through the tube 11, ignites the combustible mixture therein.

When the fuel-air mixture in the tube 11 is ignited it burns and expands. Thereupon the pressure in the tube 11 forces the products of combustion out of the tube. One portion of the products of combustion leaves the tube through the open rear end 13 exerting a reaction upon the combustor tending to move it in the opposite direction, that is to say to the left as viewed in the drawing. in order to employ this force effectively the tube 11 is reduced rearwardly in cross section as illustrated at 20 and the rear part of the tube is extended for an appreciable distance behind this point, as illustrated in Fig. 1.

Another portion of the expanding products of combustion leaves the tube 11 through the openings 15, moving reversely with respect to the entrance of air into the tube through these openings.

In order to direct air elfectively into the tube 11, and in order to realize the objects of the invention with respect to reverse flow of the products of combustion through the openings 15, an annular collar 21 is disposed to surround the tube 11 between its closed end 12 and the shoulder 14 formed thereon. The annular collar is conveniently fixed in place by fins or other conventional means (not shown). The annular collar 21 is streamlined to offer a minimum resistance to the air upon movement of the air relatively to the combustor 10 from left to right as illustrated in Fig. 1. Thus the annular collar is bowl-shaped having an axial passage therethrough of a diameter slightly less than that of the larger or main section of the tube 11 and having an interior bell-shaped space between the passage and the larger end of the collar 21. The annular collar is disposed to surround the forward end section of the tube, and the bell-shaped expansion of its bore surrounds the transition section of the tube and faces rearwardly thereof. Accordingly, an annular passage 22 is provided between the collar 21 and the tube, this annular passage narrowing slightly from front to rear and serving to direct air passing therethrough toward the openings 15. See Fig. 2. Thus, upon movement of the combustor to the left as shown in the drawing, or upon movement of air to the right, air enters the tube 11 through the openings 15 therein rearwardly of the fuel ring 16 where it mixes with the fluid fuel which is projected through the spray orifices 17. Upon ignition of the resulting combustible mixture, as by the spark plug 19, a sudden expansion of the mixture results and the products of combustion leave the tube 11 as previously described.

It is noted however, that the force of the expanding mixture as it burns causes the products adjacent the openings 15 to be projected through these openings sub- 3 s tantially radially of the tube 11. The annular collar 21 is formed to take advantage of this action and to change the direction of flow of the products of combustion through the openings 15 to give additional propulsive impulse to the burner.

In order to obtain the result just described the rear portion of the annular collar 21 is bell-shaped and surrounds the openings 15 in the shoulder 14 in a manner to cause the products of combustion impinging thereon to be deflected rearwardly of the burner. See Fig. 3. Thus, where the invention is applied to jet propulsion, a reaction is exterted upon the annular collar 21 which gives a propulsive impulse to the unit tending to move the combustor in the same direction as does the reaction to the products of combustion leaving the open rear end 13.

Clearly air cannot enter and leave the openings at the same time. Consequently, the action of the con1- bustor is intermittent. First air passes through the annular passage 22 between the collar 21 and the tube 11 and is directed into the tube through the openings 15 to mix with the fluid fuel spray projected through the spray orifices 17. See Fig. 2. A combustible mixture being thus formed, the spark plug 19 ignites it. Thereupon pressure builds up in the tube 11. In consequence the products of combustion leave the burner through the open rear end 13 and, in a jet propulsive unit, impart a propulsive impulse to the burner. At the same time the built up pressure in the tube 11 expels anotherportion of the products of combustion through the openings 15. The flow of such portion of the products of combustion is substantially radially of the tube 11 and impinges upon the bell shaped after portion of the annular collar 21 to be deflected rearwardly of the burner. See 'Fig. 3. Thus in a jet propulsive unit, an additional propulsive impulse is applied to the combustor.

The invention also contemplates, in one form, applying the entire propulsive impulse of the combusting gases to the burner through the annular collar 21. There may accordingly be no ejection of the products of combustion through an open rear end 13, but the combustor may have a closed rear end 13a as shown in Fig. 5. In this modification, the internal pressure against rear end 13a is nullified by similar pressure against forward end 12.

These internal forces represent no significance in the operation of the combustor shown in Fig. 5. The only external force (except air resistance) taking place during the combustion period is produced by the deflected expulsion of combustion products passing through the rearwardly facing bell-shaped exit portion of collar 21.

The present invention provides a valveless intermittent or pulse combustor which is simple, eflicient and practical. A minimum resistance is offered to the flow of air into the burner, and a minimum resistance is also offered to reverse movement of the products of combustion out of the burner. The direction of the reversely flowing products of combustion is advantageously changed to direct the products of combustion in the same direction as that of the air entering the burner. In the case of a jet propulsive unit, an additional propulsive impulse is thus given the unit.

The forms of the invention here described and illustrated in the accompanying drawing are presented as examples of how the invention may be applied. Other forms, embodiments and applications of the invention, coming within the scope of the appended claims, will of course, suggest themselves to those skilled in the art.

Iclaim:

1. A valveless combustor comprising a tube having a closed end and an open end, a shoulder connecting the body of said tube with said closed end, said shoulder being provided with openings therein, a separate annular collar substantially coaxial therewith and spaced from said tube surrounding said shoulder openings, said collar comprising a forward entrance passage constructed and arranged to intermittently admit air into and withhold air from said tube and a rearwardly disposed exhaust passage constructed and arranged to eject deflected combustion products, said shoulder openings constructed. and arranged to intermittently channel air into said combustion tube from said collar entrance passage and direct combustion products from said tube against said exhaust passage for propulsive expulsion.

2. A valveless combustor comprising a tube having a closed end and an open end, a shoulder connecting the body of said tube with said closed end, said shoulder being provided with openings therein, a fuel supply element in said tube for spraying fuel into the air in said tube, igniting means for fuel-air mixture in said tube, a separate annular collar substantially coaxial therewith and spaced from said tube surrounding said shoulder openings, said collar comprising a forward entrance portion constructed and arranged to intermittently admit air into and withhold air from said tube and a rearwardly disposed bellshaped exhaust portion constructed and arranged to eject deflected combustion products therefrom, said shoulder openings constructed and arranged to intermittently channel air into said combustion tube from said collar entrance portion and direct combustion products from said tube against said bell-shaped exit portion for propulsive expulsion.

3. A valveless intermittent combustor comprising: a tube of circular cross-section, said tube having a closed forward end section, a main section of larger diameter than said forward end section, and a transition section of progressively increasing diameter between the forward end section and the main section of said tube, the transition section of said tube having openings therein for admitting air to said tube and permitting combustion products to leave said tube therethrough; and a bowl-shaped collar having an axial passage therethrough of a diameter slightly less than that of the main section of said tube and having an interior bell-shaped space between the passage and the larger end of said collar; said collar being disposed to surround the forward end section of said tube, being spaced therefrom with the inner edge of its bellshaped interior substantially surrounding the junction of the forward end section and the transition section of said tube, and the rear edge of said bowl-shaped collar surrounding the main section of said tube beyond the openings formed in the transition section thereof; whereby air moving along said tube axially thereof from its forward section toward the main section will pass between said collar and said tube to enter the main section through the openings in the transition section of said tube, and whereby pressure in said tube will leave the openings in its transition section substantially radially and will be turned in the bell-shaped space of said collar to move rearwardly of said tube.

4. A valveless intermittent combustor comprising: a

tube of circular cross-section, said tube having a closed forward end section, a main section of larger diameter than said forward end section, and a short transition section of progressively increasing diameter between the forward end section and the main section of said tube, the transition section of said tube having openings therein for admitting air tosaid tube and permitting combustion products to leave said tube therethrough; and a bowlshaped collar having a bore therethrough larger than the greatest external diameter of the forward end section of said tube and a bell-shaped expansion of the bore therein extending to the larger end of said collar; said collar being fixed with the bore therethrough symmetrically surrounding the forward end section of said tube and the bell-shaped expansion of its bore surrounding the transition section of said tube; whereby air moving along said tube axially thereof from its forward end section toward the main section will pass between said collar and said tube to enter the main section through the openings in the transition section of said tube, and whereby pressure 5 in said tube will leave the openings in its transition section substantially radially and will be turned in the bellshapecl space of said collar to move rearwardly of said tube.

References Cited in the file of this patent UNITED STATES PATENTS 2,496,351 Mazzoni Feb. 7, 1950 6 Fylfe Nov. 28, 1950 Britton et al Aug. 7, 1951 FOREIGN PATENTS Great Britain July 10, 1947 

